Outdoor goods - don't use them outdoors

It's been windy the last few days. Not a typhoon or anything, but a strong wind blowing right through our garden.

The house doesn't seem to mind this, but the tarps we've been using to provide shade have been flapping like they're literally three sheets to the wind. That expressions refers to the setting of sails--a sheet, as is not at all obvious to the non-nautical, is a piece of rope tied to the loose end of a sail. This can change the sail from being close-hauled, almost in line with the ship when you're sailing upwind, or let right out for a broad reach or a dead run.

The house doesn't look drunk, but the strong wind has been pulling pegs out and letting the tarps wave around.

The wind was blowing so strongly the other evening that I undid the guy ropes from the pegs, went up to the balcony and furled the tarp, rolling it up and tying it along the top of the railing so that it would not flap any more. I started thinking about getting a more ship-shape arrangement out there, so the tarps can more easily be drawn in and out to suit the sunshine and wind.

The sound of wind is not a bad sound, but there is a lot of energy in the wind, and hopefully the balcony which the tarps are tied to will not sail away from the house. At night we don't need the tarp, but if it's a sunny and windy day in September, we want to keep the sun out. Perhaps I can rig up some halyards for next year, so that the tarps can go up and down with the weather, and possibly be set differently for the sun. Low and in the East for breakfast; high and to the south for lunch; letting the stars in at night.

One issue is that the guy ropes have been breaking a lot over the past few days. This is probably a combination of the heavy wind and fatigue over a month of holding the tarp through all weather. The points of failure were not at places with friction, at the knots, in the eye connecting to the tarp or at the peg, but in the middle of the rope.

I wonder also whether UV radiation has been breaking down the material of the rope. I know that UV can be very damaging. This would be ironic as the tarp is called a "UV Hexagon Tarp" and claims to "protect UV". No doubt "UV" is more of an advertising slogan than an optical description. And anyway the tarp claimes to protect anyone sitting under it from UV; it does not claim that the ropes holding it up are UV resistant. Or perhaps "protect UV" is literal, and it is doing as little as it can to impede the ultraviolet raise on their long journey from the sun to our subcuticular carcinomas.

Anyway, I'd hoped all the parts of these outdoor goods would last more than a month outside, rather than being good for a couple of weekends and being stored away in a cupboard for years in between.

The first tarp we used tore in two on a very windy day at the beginning of August. We'd had it for years and it didn't owe us much. It was a good excuse to buy a newer tarp to add to our camping inventory. After some sewing we can now use the original as two different tarps, which I suspect will be less susceptible to wind than one large piece of cloth.

Adding insult to insulation

While browsing the Weird Wired World for shades to hang over our terrace, I came across a few that claimed to be insulation. Like this one on amazon. At least they claim to be 断熱 dannetsu, which I've always translated as insulation. Maybe this is just a bit of a false friend and the meaning of the Japanese word is wider, but I think it's just another example of thermal ignorance, which transcends linguistic, as well as national and cultural borders.

The shades--bits of fabric to stretch out in front of windows or over terraces--are certainly going to be stopping radiation and cutting ultra violet. To put it more precisely, I should just say that they will stop radiation, as UV is a kind of radiation. That's what the websites were saying, though. 遮熱 shanetsu is the Japanese word for thermal shielding, but I'm not completely sure  if that is the English word for it.

Hanging a piece of fabric in front of your window is going to have very little insulation effect. For a start it's not really thick enough to insulate. You don't see many people heading out on a cold winters day holding a plastic sheet next to them to keep the heat in, although of course it would be better than nothing. Even if it were insulating, the fact that it's hanging a few centimetres away from the window, or stretched out at 60 degrees to the window, means that any insulation effect will be severely compromised by the hot air sneaking around the sides. 

Awnings and shade

At some point, probably in a couple of weeks, we're going to want some shade over the terrace. Otherwise we may get hot feet. There is 20 cm of concrete under the tiles, which should sink some of the heat, but in direct sunlight, it's going to get hot. The range of options, and corresponding range of costs is quite wide. 

The ideal solution would be a shop-style awning, that can be drawn in or out as we like it. My feeling is that we should put up some semi permanent shade over the terrace at the beginning of the summer, and take it down at the end of summer. My wife prefers something much more variable, which may be a cultural difference. The same thing seems to happen with heat in Japan and the UK. In the latter, houses usually have central heating, so you set the temperature you want, then it is warm enough. Japanese houses typically have fan heaters and air conditioners, so if the temperature is not how you want it, you can press a button.

I'm not sure whether it's enough to have a button like the one next to the traffic lights that you press, and it says "please wait". These are often not connected to the traffic lights, but people feel much better if they have something to press. 

Or there's the joke about the Englishman, Scotsman and Irishman stuck in the desert. I must apologies for the mild racial stereotyping in this joke. If anyone takes offence, they should just remember that the Irishman was from Kerry.  

Anyway, they walk through the heat for a while, and meet a genie, who gives them a wish each. The Englishman asks for gallons of water. The genie grants the wish, the Englishman drinks and is cool and happy. The Scotsman asks for gallons of whisky. The genie grants the wish, the Scotsman drinks and is happy. Then the Irishman asks for a car door. The Englishman, Scotsman and genie look at him, and ask what on earth he wants a car door for. "Well," he replies, "If I get too got, I can wind down the window."

In our situation, of course, when it's really hot outside we will want to shut the windows. We could still do with something outside to stop the heat getting in by radiation through the glass. I think we underestimated the effect of the white-tiled terrace to the south reflecting more heat in through the windows. This probably increased the solar gain in the winter, and of course it will increase the solar gain in the summer unless we shade it.

Trawling the internet, mostly Amazon and Rakuten, the cheapest solution is canvas strips, anchored at the top to the balcony above and at the bottom pegged into the garden. There are some framed awnings for a few thousand yen, but usually only 2 or 3 metres wide and not so sturdy. Our terrace is almost 6 metres wide.

These people, Minowada, make them much wider. This place seems to sell their awnings for 400,000 yen. Tostem also has some, about half the price, but not as wide.

As an option, for another 120,000 yen, they have a wind detector, that will automatically close the awning if the wind gets up. We're not in a particularly typhoon-prone area of Japan, and actually the terrace is probably well sheltered as it's surrounded by houses. Perhaps we can design ourselves not to put the awning out when there's any chance of wind. 

My wife's biggest worry is the heat, and influence from the terrace into the house. According to calculations, the windows will let in some of the heat of the sun when it's low and shining through them in the winter, but much less in the summer when it is higher. This is for about three reasons: one is that as the sun gets higher the angle becomes more acute, and more sunlight is reflected from the window. Another reason is that as the angle gets more acute, there is more glass to go through, so less heat gets through. At the best of times, the south-facing windows will only let in 60% of the sunlight, and that's because they are special high-g glass. Another reason is that in the summer the sun rises north of east, so it won't be shining into the south-facing windows at all in the early morning, and the balcony above the terrace should form a complete block of direct sunlight, at least until the end of August. Some heat may be reflected off the terrace, but it's still going to be the same acute angle. As for heat getting in by conduction, this should be very small, and hardly worth bothering about. The only difficult thing will be to keep windows closed during the daytime, so the heat exchanger will start working to cool down the incoming air, rather than letting in hot air.

At the moment we have a camping flysheet over the terrace, but may go for a slightly more sophisticated set of canvas pieces for this year at least. 

Blind faith

Originally we were going to get strips of fabric running vertically where the strings hold the blinds up. These were sold to us quite agressively as covering the holes in the blinds, stopping pinpoints of light getting through, and the pictures in the brochures made it look like they were some fancy design feature, embellishing the beauty of the blinds. 

We were struggling to decide what colour these fabric strips should be, worrying that with time the colour would fade in a different way to the blinds themselves, and I made an executive decision and said we didn't want any. Without them, the blinds look like blinds. They have fine strings attached, but we're used to that. That's what blinds look like. With the fabric, they look like blinds with bits of fabric coming down them. What made the decision for me was that they insist on having them at about 30 cm intervals, which seems to be massively over-engineered. I can see with thin flexible blinds, some extra support would help, but these slats are wooden, so there is no bending. They really only need strings at each end, and perhaps in the middle for extra stability. They're made of wood, not lead, and are not that heavy.

When they recalculated the price without the strips of fabric, it went down by over 10%. They were trying to rob us blind! I suppose that's just business. Tell your customers they're getting a massive discount. Try to add as many extras to your products as possible. Tell the customer how much they need them. Charge extra for each one.

We had to choose colours for the slats themselves, and the choice was white, matching  the walls, and window frames, or dark brown, matching the shelves and cupboards. Actually there was a wider range of choices than this, but within our colour scheme, those were the two choices. We chose white, which looks good, but I have that nagging feeling we should have chosen dark brown. The ideal would have been white on one side, and dark brown on the other. We suggested this, and tried to make the blind man see, but it was impossible. They don't make them. We'll have to just paint one side of them!

White reflects better, so it may prevent heat getting in in the summer. I'm not sure exactly how effective this will be as the three window pains do their fair share of reflecting. The G value of the windows is 50%, so half of the radiation gets through, and the other half is reflected. This will also happen on the way out, so once the radiation gets into the house, half of it will stay. Actually, a certain amount is going to be heating up the middle pain, but keeping it simple, drawing the blinds on a hot day is going to stop direct radiation getting into the room, and it will feel less hot, although it will only halve the amount of heat getting into the house. It'd be nice to have a radiation meter so that we can tell exactly how much radiation is coming in. 

Another advantage is that white is lighter, so the room will be less dark. Brown, on the other hand, absorbs more heat and radiates more heat. In the winter brown would be better if we ever have the blinds down in the day time, as it will get the heat into the house, but not the radiation. Also brown will probably feel warmer when we have the blinds down at night. Anyway, the white blinds will be a lot warmer than nothing. We'll have to give it a year.

Perhaps we'll look back and think we were colour blind, but we had to choose something!

At the moment every time I go past the blinds, I put them up so I can see outside, and every time my better half goes past, she puts them down, worried about the neighbours looking in. We need to work more on the garden.

The blind man came to see the house

With our triple-glazed argon-filled low-e windows we don't really need curtains. At least that's what the people selling the windows said. Actually when it's really cold outside, some blinds would help reducing heat loss through radiation, especially with the lack of emmissivity in the room. Also blinds give us a bit more privacy, and may help keep some of the summer solar radiation out, although I think geometry and the balcony will be more effective. Just because we don't really need them, doesn't mean we don't want them.

Anyway, for aesthetic purposes as well as mitigating the flow of heat, we want broad wooden venetian blinds along the ground floor on the south. From a privacy perspective, it's easy to angle such blinds so that it's possible to see out, down to our terrace and garden, without being seen into from the higher windows of the neighbouring buildings.

We also need a blind in the washitsu, the tatami room, for privacy when guests are staying in there. Personally I'm quite happy for anyone who gets to the front door to be able to peer into that room, but this is not a unanimous view among members of the household. I was originally hoping that we'd get a shoji paper door across that window, but at some point it was decided that this would not match the Germanness of the window. Perhaps sliding shoji doesn't go with swinging windows. Perhaps for this reason, perhaps for other reasons best known to the architect, there is very little clearance between the top of the window and the ceiling in this room. Around 40 mm from the ceiling to the top-sill, then 35 mm from the top-sill to the top of that window sash when it opens, inwards. That's only 75 mm, which is not a lot to fit a blind in when it rolls up to the top, as it inevitably will. And I have some memory of the ceiling having been raised, so there would have been much less space to put the blind in.

Perhaps this was in the architect's blind spot. Or perhaps he just turned a blind eye. 

The blind we were looking at for this room was kind of a double roll blind, that has alternating strips of transparent and opaque material doubling back on itself, so, as you let the blind down, it goes from being opaque to having strips you can see through. When I say opaque, it's not completely opaque like air-raid curtains, or the wall next to the window; more strictly speaking it's translucent. The critical part for our concerns is that the width of the roll, when rolled up, is 78 mm, a whole 3 mm wider than the gap between the wall and the open window. Not ideal. Because the blind is doubling back, it is actually twice as long as the height of the window, so a single roll-blind would probably be significantly thinner, and should fit in the space. It wouldn't give us this find level of transparency adjustment though. Another kind of these blinds has two different rolls, with different colours, and presumably each roll would be thinner, but that blind seems only to be attachable in a vertical orientation, with one roll on top of the other. You could say it's a case of the blind leading the blind. 

Onto the South side, the middle big window has a bit of ceiling sticking out on the left side, and a beam coming across on the right side, so we are limited for clearance there too. There is about 150 mm from the protruding ceiling to the window top-sill, then about 40 to the top of the window sash when it opens. The stark choice is either a narrow blind, where there is a few centimetres' gap on each side, or a shorter blind, but the shorter blind would need to be half a metre shorter to make a significant difference to the thickness of the slats when closed. 

One suggestion to get around this was to make the blinds wider than the box with the mechanism in it. It looks like the total height of mechanism plus slats was over 200 mm, but taking away the box width from this, the width of the slats seems to be less than the 150+40 gap we have between the protruding ceiling and the top of the beam. The blind man said he was going to find out from the manufacturers whether they could produce blinds like this, where the slats are wider than the box. He got back later saying that they could make blinds like that, but the whole thing actually needed about 300 mm, so there wouldn't be enough room for the slats. I don't completely believe this, as usual, and would like to see some numbers and actual clearances before a decision is made. I can appreciate their desire to leave wide clearances, and plenty of margin for error, but I also have a strong desire to have blinds that will cover the whole of the window reveal. 

And just in case you thought you'd seen the last of the blind puns, I'm going to blindside you with another one. 

What comes down sometimes doesn't go up again.

From the beginning of February, when it started getting to around minus ten each night, we were putting down the shutters on the upstairs windows each night. They may have some insulation effect, but their cutting down on heat radiating from the house is probably more significant.

Joe, who is eight, correctly surmised that the best time in the morning to put the shutters up is when the light comes on to show that the solar panels are producing electricity, and the shutters should come down in the evening when the light goes out. According to the passive house software, the heat coming in through the south-facing windows is 790 kWh in February, which is over 20 kWh per day. This goes up to 927 kWh in January, over 30 kWh per day. It's 843 in December and 743 in March. Overall, the south facing windows bring in over three times more heat than they lose, so even if it's very cold outside, any solar radiation coming in is going to make up for the thermal losses, and certainly be more of a benefit than any increased insulation from the shutters.

Anyway, I got back one evening to find that one of the shutters had come down a few centimetres. I assumed this had been partially put down, so I switched it to come down properly. It didn't, but there were whirring noises. I switched it to go up. More whirring noises. 

Now this shutter happens to be outside the window opening onto the balcony. Lucky, I thought, as I can just open the window and try to help it up or down. Actually I got Joe to help with the controls, while I stepped out onto the balcony to try pushing the shutter up while he was switching the shutter to close. I thought perhaps it was a little disengaged.

As it turns out, it was more than a little disengaged, and after some more whirring and a little clunking, the whole of the shutter came crashing down to the bottom, leaving me standing on the balcony in bare feet on a very cold afternoon. It was impossible to get the shutter up again, as it was not coiling properly inside its case. The shutter case uses some kind of six-pointed star screwdriver, so I couldn't open that to get the shutter up. I was stuck.

I considered climbing down from the balcony, but decided it was best to appeal to my better half's better nature and get her to bring a ladder out. The sharp tongue of a wife who is both angry and right, while certain to cause some injury, would be much less painful than potential injuries from sliding and landing on the hard tiles below. 

Before fixing this, the suppliers, who also provided our windows, needed to get parts for the disengaged shutters, and there was a chance that they would not be able to fix it until we got back from our travels. They assumed that we would be leaving the shutters down while we were away, but I was looking at the thermal gain from these windows. Of a total almost 16 square metres of glazing on the south side of the house, the shutter in question was covering a double window, with 1.5 square metres of glazing. That's 10%, so a couple of kWh a day. The equivalent of a heater on for an hour. It can still be quite chilly at the end of March, so we didn't want to be turning heat away while we were away.

As it happened, the parts arrived and it was fixed in time. What had happened, apparently, was that the for the motor to stop when the shutter was going up had been set above the actual level of the shutter when fully wound up. The switch goes three ways: up, off and down. If the shutter is down, when the switch is switched to up, it will go up until you switch it to off again, or if you leave it it will go all the way to the top, then it should switch off inside, even if the switch is still set to up. So the first few times we used it, we had obviously been very careful and attentive, marvelling at the wonder of this technology, and staying to switch it off as soon it reached the top. After a week or so, we switched it to go up and left the switch, confident that it would automatically stop. However, it wasn't switching off and the motor was still working away on the shutters, presently rending them from the axle. 

All is now well, and I'm beginning to wonder what temperature it is actually worth putting the shutters down at night, as the effects on radiation must be minimal.

South side, revisited

To the south of the house, we have a lovely terrace. Actually, it's a slab of concrete covered in scaffolding and deteriorating kenaf board at the moment, but it will soon be a lovely, tiled, terrace, where we can sit out in the sun, or snow.

We need some shade for the downstairs windows, and we need a bit of a balcony upstairs, to hang out washing or futons, or clean windows, so the plan is for a balcony running the whole length of the south wall, sticking about 60 cm out from the house. With some care, it should be possible to get this the right height so there is around 45 degrees from the edge of the balcony to the top of the window, and it will let in every drop of direct winter sunlight until the end of February, and around 60 degrees from the edge of the balcony to the bottom of the window, so it will keep out all the summer sun from the end of April. Upstairs we have shutters that will allow some variation.

This is basic passive solar design, and not really rocket science.
We also would rather not have pillars sticking up in the middle of the terrace, which is in front of the middle window and the kitchen window. This means that some kind of beam needs to cross a span of around 5 metres, with minimal thickness. The idea in the final plan was to put up six pillars around the terrace, one in each corner, and one in the middle next to the bit of wall between the two windows, and another opposite that on the south side of the terrace.

These were all made of wood, and there seemed to be a lot of it. Although I've been demanding a 45 degree line to demarcate no-building zone up and away from the window, the actual results from the Passive House software on how obstacles will reduce incoming sunlight are more subtle.

The best estimate at the moment is that all the windows in the house will lose 2,400 kWh per annum, but they will gain 5,400 kWh in solar gain, so the windows are bringing in 3,000 kWh net, over the winter heating period. In very rough financial terms, we could call this 30,000 yen per annum, if we budget 10 yen for each kWh. This is the thermal output of the windows if we look at them as a heater. Of course windows in Japanese houses usually only work as heaters in the summer, and in the winter they are very effective coolers. They also work as dehumidifiers, turning humidity into condensation on the inside of the glass, and on the frames.

Of course we also got the windows to provide natural light, and to give us a view. Looking at the simple cost benefit of insulation, it would make a lot more sense to have no windows, and use electric light inside, but we don't want to live in a cave.

The house next door to the south, that I've estimated to be five metres tall and 16 metres away, will apparently reduce the amount of heat coming in by almost 300 kWh per annum.  So the house next door has already taken away 10% of this total. 3000 yen per annum.

The amount of heat coming in changes with each adjustment of the windows in or out of the wall, and depending on what we do to each side, above, and to a greater extent in front of them. The passive house software estimates 5% of heat will be lost because the windows are not clean all the time.

I'm assuming that above the ground floor windows, there is a balcony 600 mm higher, sticking out 600 mm. If this comes down by 10 mm, we lose 16 kWh per annum. If, instead, it sticks out another 10 mm from the house, we lose 42 kWh per annum. Only 160 yen or 420 yen per year.

A bigger problem is that the horizontal part of the frame on the south side of the terrace was going to obstruct the sun's rays coming into the house. Around 80 kWh for a 120 mm beam, and 160 kWh for a 240 mm beam. That's 1,600 yen per annum. Over 5%.

So, we're getting rid of the pillars at the south of the terrace, and the wooden frame, and I was thinking about putting a frame of square-section steel on top of six wooden pillars. If it's steel, it should be able to span the five metres above the terrace without needing to be too thick. I was trying to work out the deflection, and it looks like a 150x150 mm beam will only move about a centimetre if I stand in the middle (one Mark is about 125 Newtons). As there are going to be two beams, the frame will move a bit less than this, and should feel solid enough. And anyway, the main job is to provide shade in the summer, and being able to walk along it is a bit of a bonus.
This sounds to be a non-starter though. A steel frame is going to be really heavy, and would need a crane to get it in place. Now that there's a house next door, that would probably mean a big crane to lift it over the whole building. Steel is a lot more expensive than wood, too.
After a little discussion it seems possible to loose the south side pillars and use a bracket from the pillar in the middle of the north side so we don't need a pillar in the middle of the terrace. The beam at the south may be a little thicker, but the effect on solar gain is at least five times less than the beams and pillars at the south sides. It should also cost less.
Another compounding issue is that we want to be able to get some shade over the terrace, probably for most of the summer. If we have some kind of permanent frame, it would be easy to hook up some fabric shading over it. If there is just a balcony, we could get some something like a shop awning that could be extended and retracted more freely, although this could be more expensive and may put a lot of torque on the balcony.

Also, I was wondering about growing vines up the frame, maybe kiwi fruit, which would produce shady leaves in the summer, and just leave branches in the winter. Of course the bare branches would still reduce the thermal gain, and this seems to contradict everything I've said above.
I do like kiwi fruit though. Apparently they have six times the vitamin C of oranges.